From: Mikulas Patocka <mpatocka@redhat.com>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: rientjes@google.com, mhocko@kernel.org, okozina@redhat.com,
jmarchan@redhat.com, skozina@redhat.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, dm-devel@redhat.com
Subject: Re: System freezes after OOM
Date: Thu, 14 Jul 2016 08:29:32 -0400 (EDT) [thread overview]
Message-ID: <alpine.LRH.2.02.1607140827330.15554@file01.intranet.prod.int.rdu2.redhat.com> (raw)
In-Reply-To: <201607142001.BJD07258.SMOHFOJVtLFOQF@I-love.SAKURA.ne.jp>
On Thu, 14 Jul 2016, Tetsuo Handa wrote:
> Michal Hocko wrote:
> > OK, this is the part I have missed. I didn't realize that the swapout
> > path, which is indeed PF_MEMALLOC, can get down to blk code which uses
> > mempools. A quick code travers shows that at least
> > make_request_fn = blk_queue_bio
> > blk_queue_bio
> > get_request
> > __get_request
> >
> > might do that. And in that case I agree that the above mentioned patch
> > has unintentional side effects and should be re-evaluated. David, what
> > do you think? An obvious fixup would be considering TIF_MEMDIE in
> > mempool_alloc explicitly.
>
> TIF_MEMDIE is racy. Since the OOM killer sets TIF_MEMDIE on only one thread,
> there is no guarantee that TIF_MEMDIE is set to the thread which is looping
> inside mempool_alloc().
If the device mapper subsystem is not returning objects to the mempool, it
should be investigated as a bug in the device mapper.
There is no need to add workarounds to mempool_alloc to work around that
bug.
Mikulas
> And since __GFP_NORETRY is used (regardless of
> f9054c70d28bc214), out_of_memory() is not called via __alloc_pages_may_oom().
> This means that the thread which is looping inside mempool_alloc() can't
> get TIF_MEMDIE unless TIF_MEMDIE is set by the OOM killer.
>
> Maybe set __GFP_NOMEMALLOC by default at mempool_alloc() and remove it
> at mempool_alloc() when fatal_signal_pending() is true? But that behavior
> can OOM-kill somebody else when current was not OOM-killed. Sigh...
>
> David Rientjes wrote:
> > On Wed, 13 Jul 2016, Mikulas Patocka wrote:
> >
> > > What are the real problems that f9054c70d28bc214b2857cf8db8269f4f45a5e23
> > > tries to fix?
> > >
> >
> > It prevents the whole system from livelocking due to an oom killed process
> > stalling forever waiting for mempool_alloc() to return. No other threads
> > may be oom killed while waiting for it to exit.
>
> Is that concern still valid? We have the OOM reaper for CONFIG_MMU=y case.
>
next prev parent reply other threads:[~2016-07-14 12:29 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <57837CEE.1010609@redhat.com>
[not found] ` <f80dc690-7e71-26b2-59a2-5a1557d26713@redhat.com>
[not found] ` <9be09452-de7f-d8be-fd5d-4a80d1cd1ba3@redhat.com>
2016-07-11 15:43 ` System freezes after OOM Mikulas Patocka
2016-07-12 6:49 ` Michal Hocko
2016-07-12 23:44 ` Mikulas Patocka
2016-07-13 8:35 ` Jerome Marchand
2016-07-13 11:14 ` Michal Hocko
2016-07-13 14:21 ` Mikulas Patocka
2016-07-13 11:10 ` Michal Hocko
2016-07-13 12:50 ` Michal Hocko
2016-07-13 13:44 ` Milan Broz
2016-07-13 15:21 ` Mikulas Patocka
2016-07-14 9:09 ` Michal Hocko
2016-07-14 9:46 ` Milan Broz
2016-07-13 15:02 ` Mikulas Patocka
2016-07-14 10:51 ` [dm-devel] " Ondrej Kozina
2016-07-14 12:51 ` Michal Hocko
2016-07-14 14:00 ` Mikulas Patocka
2016-07-14 14:59 ` Michal Hocko
2016-07-14 15:25 ` Ondrej Kozina
2016-07-14 17:35 ` Mikulas Patocka
2016-07-15 8:35 ` Michal Hocko
2016-07-15 12:11 ` Mikulas Patocka
2016-07-15 12:22 ` Michal Hocko
2016-07-15 17:02 ` Mikulas Patocka
2016-07-18 7:22 ` Michal Hocko
2016-07-14 14:08 ` Ondrej Kozina
2016-07-14 15:31 ` Michal Hocko
2016-07-14 17:07 ` Ondrej Kozina
2016-07-14 17:36 ` Michal Hocko
2016-07-14 17:39 ` Michal Hocko
2016-07-15 11:42 ` Tetsuo Handa
2016-07-13 13:19 ` Tetsuo Handa
2016-07-13 13:39 ` Michal Hocko
2016-07-13 14:18 ` Mikulas Patocka
2016-07-13 14:56 ` Michal Hocko
2016-07-13 15:11 ` Mikulas Patocka
2016-07-13 23:53 ` David Rientjes
2016-07-14 11:01 ` Tetsuo Handa
2016-07-14 12:29 ` Mikulas Patocka [this message]
2016-07-14 20:26 ` David Rientjes
2016-07-14 21:40 ` Tetsuo Handa
2016-07-14 22:04 ` David Rientjes
2016-07-15 11:25 ` Mikulas Patocka
2016-07-15 21:21 ` David Rientjes
2016-07-14 12:27 ` Mikulas Patocka
2016-07-14 20:22 ` David Rientjes
2016-07-15 11:21 ` Mikulas Patocka
2016-07-15 21:25 ` David Rientjes
2016-07-15 21:39 ` Mikulas Patocka
2016-07-15 21:58 ` David Rientjes
2016-07-15 23:53 ` Mikulas Patocka
2016-07-18 15:14 ` Johannes Weiner
2016-07-14 15:29 ` Michal Hocko
2016-07-14 20:38 ` David Rientjes
2016-07-15 7:22 ` Michal Hocko
2016-07-15 8:23 ` Michal Hocko
2016-07-15 12:00 ` Mikulas Patocka
2016-07-15 21:47 ` David Rientjes
2016-07-18 7:39 ` Michal Hocko
2016-07-18 21:03 ` David Rientjes
2016-07-14 0:01 ` David Rientjes
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=alpine.LRH.2.02.1607140827330.15554@file01.intranet.prod.int.rdu2.redhat.com \
--to=mpatocka@redhat.com \
--cc=dm-devel@redhat.com \
--cc=jmarchan@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=okozina@redhat.com \
--cc=penguin-kernel@I-love.SAKURA.ne.jp \
--cc=rientjes@google.com \
--cc=skozina@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).